Engine cooling means



Nay. 23, 1948. f A. L. HIGHBERG 2,454,696

f ENGINE cooLING mams Filed Dec. 6, 1944 V 2 Sheets-Sheet 2 Patented Nov. 23, V'1948 'insiemi ENGINE COOIiING MEANS Axel L. Highberg, West Hart to United Aircraft Corp Conn., a corporation oi' Application December s, 1944, semi No. 566,870

proved means for controlling the speed of an engine cooling fan in accordance withcooling re- Vquirements of the engine.

Another object of the invention is to provide improved hydraulic drive means for drivingl an engine cooling fan by the engine at varying speeds relative to engine speed and in `accordance with variations in the temperature ofthe engine, by which adequate cooling of the engine is provided with a minimum oi engine power.

A further object of the invention is to provide improved temperature responsive means for controlling the operation of engine cylinder cooling means which is quickly responsive to changes in temperature at the hottest part of the engine cylinder.,

A further object of the invention is generally to improve cooling means for aircraft engines.

Othr objects and advantages of the invention will be apparent from the following detailed de- 25 scription of two embodiments thereof, shown in the accompanying drawings for purposes of illustration. f

In these drawings,

Fig. 1 is a schematic view of an internal combustion engine having a cooling fan driven by the variable speed, thermostatically controlled drive comprising one embodiment of the invention.

Fig. 2 is a vertical static valve of Fig. l

Fig. 3 is a section coupling. A k

Fig. 3a is a section illustrating the ring valve in the low speed coupling.

Fig. i is a diagram of the iluid system.

Fig. 5 is, a vertical section through an enginej cylinder showing a modified arrangement of the thermostatic valve.

Fig. 6 is a sectional view on line 6 6 of Fig. 5.

Fig. 7 is a view similar to Fig. 1 showing a modifled form of temperature control for the fluid couplings, and

Fig. 8 is an enlarged vertical section through the fluid valve of Fig. 7.

The engine i0 is a conventional air-cooled aircraft engine having cylinders, one of which is shown at I 2, arranged radially about a crankshaft I4 which, in the illustrated embodiments, is adapted to drive a pusher type propeller (not shown) r The cylinders are provided with usual section through the thermoon an enlarged scale.

through the low speed uld llings 22 and 24 driven ford, Conn., signor oration. East Hartford, Delaware a claims. (ci. 12s-m) A i6 which are`-coo1ed by a stream of air I8 mounted on a shaft 20 coaxial with cooling fins from a fan shaft I4.l

The fan is driven at gradually varying speeds over a wide speed range through low and high speed ratio driving trains including fluid coupfrom a gear 26 on shaft 2l. The shaft 28 may `be drivenl from a source of power separate from the engine if desired, but is preferably driven by the engine I0 and may advantageously be an extension of engine crankshaft I 4. The fluid couplings 22 and 24 are mounted on fixed hollow shafts 30 and 32 respectively through which working iluid is supplied to the `couplings as hereinafter described.

The low speed coupling l22, shown in detail in Fig. 3 has its driving member, or impeller, 34`

carried -by a sleeve 36 journalled on shaft 20. This sleeve also carries a gear 38 meshing with drive gear 26. The driven member, or runner, 40 of coupling 22 is carried by a sleeve 42 Journalled on shaft 30 and this sleeve is connected through a low speed gear drive 44, 46 to the ian shaft 20.

The high speed coupling is 'generally identical, having impeller and runner sleeves 48 and 50 respectively journalled on hollow shaft 32. `Sleeve 48 also carries a gear 62 meshing with drive.

gear 26, while sleeve is connected through a high speed gear drive 54, 66 to the fan shaft 24.

The coupling, or clutches, 22 and 24 are of the type in which the impeller and the runner are enclosed in a chamber 51 adapted to contain working fluid, and the slip between the impeller 34 which is the driving member, and the runner 40 which is the driven member, depends upon the amount of fluid present in the working chamber. The efficiency of such a coupling is a function of the slip, increasing as the slip decreases. The working chambers of couplings 22 and 24 are provided with fluid discharge passages, 'or drain holes, 58 and the amount of working fluid. in the coupling chamber at any time, and thus the slip of the coupling, and the speed of the fan I8 driven thereby, is altered by varying the amount of fluid supplied to the chamber in relation to the flow capacity of the drain passages.

Referring to Fig. 4, fluid is supplied to the couplinge from a reservoir 60 by a pump 62 through lines 64 and 66 to a thermostatic valve 68 located adjacent one of the engine cylinders which controls the flow of fluid through lines 'l0 and 12 to the low and high speed couplings 22 and 24 respectively. The uid lines 'lil and 12 extend into the axial passages in xed shaftsjl) and 32 and are xed thereto in iiuid tight relation. Referring to Fig. 3. which .ehm-1e u... 1-- --h coupling, it will be noted that iiuid line 10 has a closed'end 14 and is provided with a plurality of radial passages 18 which register with similar passages 18 in the shaft 80 and through which fluid is supplied to an annular chamber 19 from which it flows to chamber 81 of the coupling.

Means must be provided to cut on the supply of nuid to chamber 51 of the low speed coupling whenever the high plied with 'suiiicient fluid to cause the runner 40 of the low speed coupling to. be driven through gears 84, 58 and 46, 44 and overrun its own impeller .34. To this end the low speed coupling is provided with a ring valve 80 located in an annular recess 82 formed in the confronting ends of has radially dlssleeves 38 and 42. This valve posed apertures 84 which in one angular position of the valve register with like apertures 88 and 88 in the portions of sleeves overlie the ring valve. The ring valve is provided with a recess 90 in one end thereof into which extends one end oi a pin 82 carried by sleeve 38. The end walls 84 and 88 oi recess 90 are so related to the ports 84 in the ring 80 and ports 86, 88 in sleeves 42, 38 that when the sleeve 38 is rotating faster than sleeve 42 the pin 92 is abutting endwall 88 and the ports are in register. However, if sleeve 4-2 rotates faster than sleeve 86, as when the high speed coupling isdriving runner 40 and causing it to overrun its lmpeller 34, then pin 82 willabut end wall 84 and the ports will be out of register. It will be understood that this ring valve is omitted from the high speed coupling 24, oil being admitted directly from line 12 to the coupling chamber whenever the thermostatic valve admits oli to line 12.

The thermostatic valve 68 for controlling the admission of oil to the high and low speed couplings comprises vv(Fig. 2) a valve housing 81 having a central chamber 98 into which oil is delivered from the pump 82 by line 56, an upper chamber from which oil is supplied through line to the low speed coupling, and a lower chamber |02 from which oil is supplied through line 12 to the high speed coupling. The casing 91 has axial passages I4 and |08 controlled by valves |08 and I|0 respectively. The valve |08 is rigidly nxed to a, valve stem H2 guided for axial movement in the valve casing while valve I0 is carried on a short floating stem I|4 having received in an axial recess its upper end slidably in valve |08 and its stem I|2. A spring IIS in chamber |02 constantly biases the valve H8 upwardly into closed position in which it is maintained during a limited axial movement of valve |08 as determined by the distance between the base of valve |00 and a shoulder H0 on valve stem |I4. Movement of valve I8 beyond the normal position of shoulder I|8 causes valve H0 to be opened against the bias or" its spring.

The valve stem |I2 is attached to the upper end wall of a sealed expansible bellows |20 enclosed ln a fluid tight chamber |22 located at the top of valve housing 91 and adapted to contain an expansible fluid which is critical (or vaporizes) speed coupling 24 is being sup- 42 and 38 which at the optimum engine operating temperature. A

Second chamber m having heat absorbing uns |25 is mounted on the top of chamber |22 and communicates therewith through va passage |26. Chamber |24 is adapted to be at least partially filled with the expansible uid in chamber |22. Chamber |24 may be located more remote from chamber |22, if desired, and connected thereto by means of a capillary tube, in a well known manner. In the arrangement shown the entire land 88 are out of. register with engine cylinder iins valve 68 is mounted at the rear of the engine cylinder |2 where it is swept over by the stream of cooling air from fan I8 after'it has passed through the engine cylinder cooling iins I8. It will be noted that the heat absorber chamber |24 ls located adjacent the upper portion of the cylinder where its fins |25 will bein the airstream passing by the combustion chamber of the cylinder head.

In the operation of this embodiment of the invention it will ybe noted that when valve |08 is caused to be initially opened by the expansion of the fluid in chamber I ally admitted from the supply line 86, chamber 98 and valve passage |04 to chamber |00 and line 10vto the low speed coupling 22. As the volume of fluid builds up in the chamber 51 of coupling 22 the runner 40 will speed up and drive the fan I8 at increasing speed until the chamber is being supplied with sulcient fluid to maintain the chamber completely filled. The coupling 22 is then operating at its greatest efliciency i. e. with minimum slip and the fan is being driven at the maximum speed it is possible to drive it in the low speed gear ratio.

4 As valve |08 ls further depressed by the expansible fluid the shoulder |I8 on valve stem I|4 is engaged by the bottom of valve |08 and valve ||0is gradually opened to supply fluid in slowly increasing volume .to the high speed coupling until the latter is driving the fanvat full speed.

As soon as the high speed coupling begins to take over the fan drive from the low speed coupling, the runner of the latter overruns the lmpeller and, due to the frictional engagement of sleeve 42 with the ring valve 80. the latter is caused to overrun the sleeve 38, bringing the pin 82 into engagement with wall 94 of the recess 90. In this position of the valve the ports 88 port 84 in the valve and the low speed coupling being no longer supplied with oil soon drains through passages 58. Thus in each of the low and high speed gear ratlos the speed of the fan I8 is varied by controlling the amount of oil admitted to the couplings, through valve 88 to that amount necessary to drive the fan at a speed just sufilciently high to maintain .the engine cooled to the optimum temperature.

In Figs. 5 and 6 a somewhat modified construction and arrangement of thermostatic valve is shown in which the valve indicated at 68a is located in the cooling airstream on the downstream side of the engine cylinder I8 with its cooling fins |2511 projecting into the interfln spaces between the cylinder ns I8. Further, as shown in these figures, the fins |2511, on the heat absorber chamber of the valve are united to the I6 at their mutually overlapping surfaces, as by brazing or welding, so that the metal of the fins |25a is in direct heat conducting contact with the engine cylinder fins I6 at the hottest part of the cylinder I2. As shown, the fins I25a are of diminishing diameter to correspond with the increasing diameter of the cylinder fins I8 toward the top of the cylinder to provide for a uniform overlap of the interleaved iins.

With such an arrangement, the valve will be actuated in accordance with changes in cylinder head temperature by direct heat conduction fromthe head through the cylinder fins I6 to the valve iins |25a, even though the cooling air temperature and rate of flow may not have changed. l

24, working fluid is graduwith engine temperature, |30 designates the generally cylindrical housing of a rotary valve generally indicated at |34 in which a radially ported axial valve member |38 is rotatable. Member |36 has an axial inlet chamber |38 (Fig. 8) supplied Y by line 66 from pump 62 and radial ports |40 and |42 communicating with axial chamber |38. Port v |40, in certain angular positions of valve |38, registers with anoutlet chamber |44 and line 12 to the high speed coupling, While port |42, which is approximately twice as wide at its outer end as port |48, registers with an outlet chamber |46 and line to the low speed coupling, the angular relation of ,these ports |40 and |42 being such that the former remains closed while the latter is moving from fully closed to open position and the latter remains open while the former is being gradually uncovered during further opening movement of the valve to'supply oil ilrst gradually and in increasing amounts to the low speed coupling and then gradually to the high speed coupling.

The axial valve member |38 is actuated by a solenoid |48having a core |80 operatively connected with member |38 by an arm |82 which is constantly biased by a spring |84 to withdraw the core from the solenoid in the direction of the arrow in'Fig. 7. The alternating current circuit |88 for solenoid |48 also includes a variable inductance having a coil |88 associated-with a thermoresponsive device generally indicated at |60 which includes a chamber |62 containing an expansible Iluid and inserted in a recess in the cylinder head of engine cylinder |2. A'n enclosing housing |64 has a passage |88 communicating with said-chamber in which a piston |88 isV reciprocable to iron core |10 core |10 is reciprocable in an axialpassage |12 which contains a compression spring |14 constantly urging the core |10 downwardly out oi' the coil |88.

As the huid in chamber |82 expandswith increasing temperature oicylinder I2 the core |18 is moved into coil |88. causingV the inductance of circuit |88 to be gradually sequently causing a gradual decrease in current iiowing in the circuit. This decrease in current iiow through solenoid' |48 enables spring |84 to move corey |80 correspondingly out oi solenoid |48, causing valve member |88 to gradually move port |42 into register with outlet chamber |48 and supply oil in increasing quantity to the low speed coupling. Justl as the ber |48 come into complete register, the port |40 begins to register with chamber |44 to supply the high speed coupling. Thus as the temperature oi the engine cylinder increases. additional oil is supplied, first to the low' speed coupling and then to the high speed coupling to drive the ian I8 at gradually increasing speed in accordance with the cooling requirements of the engine. Y.

As a result oi' ,this invention it will be evident that means has been provided i'or controlling the speed oi anl engine cooling fan over a wide range control the movement oi asoft vby varying cooling ian` speeds relative to engine speed in accordance with variations in engine temperature, whereby adequate cooling o1 the engine into and out oi the coil I 88. TheV increased and con- 6 Vis provided with a minimum of power expended ior driving the coolingfan.

It will also be evident that improved temperature responsive means has been provided for controlling an engine cooling fari which is exceedlngly responsive to changes in engine cylinder temperature at the hottest. part of the cylinder.

While certain speciilc embodiments of the in- .vention have been shown, it will be understood that various changes may be made in the construction and arrangement oi the parts without exceeding the scope of the invention. For example, in place of the solenoid and variable inductance of Fig. 7 two Autosyn or "Belsynf units may be used to electrically couple the temperature responsive piston |86 with the valve element |38 to provide movement ofthe valve member in proportion to movement oi' the thermally responsive member.

What I claim as new and desire to secure by Letters Patent is:

1. In an internal combustion engine having a cylinder provided with cooling iins and having a variable speed ian for ing air through said iins, thermostatic means for controlling the speed of the i'an including a heat absorbing chamber containing a temperature expansible fluid and located in the cooling stream set up lby the fan, saidheat absorbing means being located in the lee of the cylinder relative to said cooling air stream and having external heat conducting ilns the adjacent peripheral portions of which are interleaved with the cooling ilns of -the cylinder.

moving a streamof cool- 2. The combination cisimea in claim 1 in which the mutually interleaved iin portions oi said heat absorbing means and the engine cylinder are united in good heat conducting relation.

port |42 and cham- 3. 4In an internal combustion yengine having a cylinder provided with spaced cooling fins and having a variable speed ian i'or moving'a stream of cooling air through said tins, thermostatic means controlling the speed of the i'an disposed in said air stream on the down stream side oi the cylinder and including a heat absorbing chambercontaining a iluid expansible over the operating temperature range oi' the engine, said chamber having external heat conducting flns'which are swept over by the air stream leaving the cylinder, whereby said thermostatic means is responsive to temperature changes or changes in rate oi'; iiow oi said air stream while the temperature of the cylinder remains unchanged, and said external fins oi said chamber and the cylinder ns having mutually interleaved portions connected in good heat conducting relation, whereby said thermostatic means is responsive to changes in cylinder temperature while the temperature and rate oi dow ot said air stream remain unchanged.

, AXEL L. HIGHBERG.

REFERENCES CITED The following references are ot record in the i'lle of this patent:

UNITED STATES PATENTS Benz et al. Jan. 8, 1948 

